1. Field of the Invention
The present invention relates to a method of displaying a sub-picture in a DVD player, and more particularly, to a sub-picture displaying method in trick play mode.
2. Discussion of the Related Art
Generally, a DVD format named digital video disc or digital versatile disc was jointly developed by ten leading consumer companies. After a DVD player has been marketed in Japan, November in 1996, the analog VHS tape has been rapidly replaced by DVD to make a great change of out life patterns.
DVD supports audio stream change, sub-picture stream change, camera angle change, and the like as well as general playback and further supports trick play and random access such as fast-forward, fast-reverse, slow-forward, slow-reverse, pause-on, pause-off, still-off. DVD provides a chapter skip function of skipping to a next chapter or retrieving to a previous chapter as well. And, DVD is equipped with a user operation function associated with various buttons as well as a menu call function enabling to select such a menu as title, root, sub-picture, audio, angle, etc. Moreover, DVD enable to put limitation on playback of scenes or discs inappropriate for children via parental management information or the like.
The sub-picture designates a simple animation such as sub-title, menu, caption, karaoke, and simple animation. And, the sub-picture is constructed with background pixel, pattern pixel, emphasis pixel-1, and emphasis pixel-2, each of which is indicated by 2-bits run-length encoded bitmap, respectively. And, binary ‘00’, ‘01’, ‘10’, and ‘11’ are allocated to the background pixel, pattern pixel, emphasis pixel-1, and emphasis pixel-2, respectively. Each of the background pixel, pattern pixel, emphasis pixel-1, and emphasis pixel-2 can take one color from 16-colors palette as well as one contrast value among sixteen contrast values designating general transparency values from ‘full transparency’ to ‘full opacity’. A data rate of the sub-picture is maximum 3.36 Mbps per stream, and a maximum size of a sub-picture unit is 53,220 bytes. The sub-picture is mostly displayed via OSD and plays a role in providing information of DVD contents in the form of characters to a user. Hence, the sub-picture is an important means for visually providing information to a user together with video.
Meanwhile, a fast-forward function of the DVD player, which provides a user with a method of enabling to play back the DVD contents at high speed, is generally used by a user as a means for searching a relatively vast amount of data within a short period of time or shifting to a specific scene. Yet, it is difficult for a user to accurately acquire the information for a corresponding section from the corresponding image moving so fast. So, the user frequently needs to repeatedly perform the fast-forward function or normal playback on the same section.
Accordingly, in performing the fast-forward function of the DVD player such as a trick play mode, a user needs to be provided with a means for providing information as well as video to give more information during a short period of time.
However, in performing the fast-forward function, the related art DVD player provides video data only but fails to perform decoding on audio or sub-picture. Specifically, in case of the sub-picture, if the fast-forward function is activated, the decoding of the sub-picture is forcibly stopped. In such a case, a user has to recognize the information of a specific section with the fast-moving images only. Hence, the user has difficulty in acquiring the accurate information of the specific section or may have to repeatedly perform the fast-forward function or normal playback on the same section.